/**
*      author: Y_Yao
*      created: 2025-04-02 15:36:28
**/

#include<bits/stdc++.h>

#define int LL
using namespace std;
using LL = long long;
const LL LLINF = 9e18;
const int INF = 0x3f3f3f3f;
const int N = 1e5 + 7;
int n;
int a[N];
int b[N];
set<int> dp;
int m[N];

void solve()
{
    cin >> n;
    for(int i = 1;i <= n;i++)
    {
        cin >> a[i];
        m[a[i]] = i;
    }
    for(int i = 1;i <= n;i++)
    {
        cin >> b[i];
    }

    dp.insert(m[b[1]]);
    for(int i = 2;i <= n;i++)
    {
        int target = m[b[i]];
        auto it = dp.lower_bound(target);
        if(it == dp.end())
        {
            dp.insert(target);
        }
        else
        {
            dp.erase(it);
            dp.insert(target);
        }
    }
    cout << dp.size() << endl;
}

signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);

    int t = 1;
    // cin >> t;
    while(t--)
    {
        solve();
    }
    return 0;
}